Questions tagged [mathematics]
The abstract study of topics encompassing quantity, structure, space, change, and other properties
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32 views
Understanding cosine-weighting?
I am studying a paper where they use a method to calculate the vertical distribution of water content (ice, water vapor, cloud water) from the amount of ice on the martian surface.
In the paper they ...
1
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0answers
23 views
How is the Point on surface tool calculated in QGIS [duplicate]
I am interested to know how the Point on surface tool works in QGIS 3. I am choosing to use this rather than the Centroids tool which works of the "center of mass" methodology because this creates a ...
1
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0answers
16 views
Applying a two step floating catchment with boundary limitations
The literature states that gravity models and the two step floating catchment area (which in itself is a version of the gravity model) method for analysing the accessibility of healthcare services by ...
3
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1answer
50 views
How to run a Epanechnikov (parabolic) decay in QGIS 3.6 field calculator
Does anyone know how you would implement a Epanechnikov (parabolic) decay to a field in QGIS field calculator. I am trying to apply varying distance decay functions in order to assess the best ...
0
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0answers
33 views
Definition for point and line geometries?
There is a common definition named "area geometry" to categorize polygons and circles and any geometry that has a surface area. I would like to know if there is an alike definition for points and ...
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0answers
62 views
calculating HRMS using NMEA sentences including GPGGA , GPGSV, GLGSV, QZGSV,QZGSA, GPGSA?
I have NMEA sentences including GPGGA , GPGSV, GLGSV, QZGSV,QZGSA, GPGSA and GNGSA. my goal is to achieve HRMS accuracy meter. produced android devices for special intent gives GP/GN GST nmea message ...
0
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0answers
18 views
is it correct calculation to achive HRMS and VRMS values from GST nmea message?
I need to calculate VRMS and HRMS values correctly using NMEA GST message.
an answered question says a calculating formula.
Calculating VRMS and HRMS from NMEA data?
$GPGST,172814.0,0.006,0.023,0....
3
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1answer
65 views
Procedure of transforming coordinates?
I'm trying to understand the math behind this transformation. I should note that I've been able to perform the transformation using GeoPandas, but I'd like to understand what is going on under the ...
0
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0answers
16 views
Finding a suitable sigma value for distance Gaussian decay function
I am trying to apply a Gaussian decay value to a set of distances measured in meters using the field calculator in QGIS.
My distances range from circa 50 to 12,000 meters. I am using the following ...
1
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0answers
26 views
How to compare centrality of points in different shaped and sized polygons
Suppose I have several polygons of varying shape and size, each containing a single point. I want to compare the centrality of each point, and determine which point is more central to its polygon. I'm ...
0
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2answers
396 views
Calculate angle between nodes or point in line in QGIS
I want to check the digitization of line in correct direction, so for that I need to know the angle of each node in line. Is that possible in QGIS?
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2answers
2k views
How to add meters to EPSG:4326 coordinates? [duplicate]
I've some lat/long in EPSG:4326 coordinate system like Eiffel Tower position : ["lat" : 48.858274,"lon" : 2.2944]
For automated tests I would like to get, for every points of my dataset, the x and y ...
1
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0answers
64 views
GRASS GIS: Getting know about stream power index (SPI) computation by r.watershed function
I need to know exact way how stream power index (SPI) is computed by module r.watershed. On the help page is that SPI is α * tan(β), where:
α is cumulative upslope area draining through a point per ...
2
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1answer
108 views
Postgresql - problem updating row with complex calculation
A calculation for the replacement value of a tree exists:
Variables:
index_price for species;
circumference of tree;
condition measures: vitality, root_injuries, stem_injuries,
crown_injuries
(A ...
1
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1answer
98 views
What's the math behind moving from a starting point in the direction of another one?
I am working with decimal-degree coordinates for a software and lack geographic background.
I want to convert the coordinates to a grid to calculate distances and then move around using standard ...
0
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1answer
52 views
Kriging: Large standard error very close to known value points
I am attempting to create surfaces of strata via Kriging in Arc GIS from borehole data. In addition to the predicted surface I also want surfaces showing 95% confidence above and below the predicted ...
1
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1answer
194 views
Formula for transforming from EPSG:4326 to EPSG:3003 or EPSG:3004
This system is used in Italy.
I came across this:
It says that lambda zero is 9° if it's to epsg:3003 otherwise if it's to epsg:3004 it's 15°
I came up with this Java code, but the result is wrong:
...
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2answers
1k views
Converting from ECEF to geodetic coordinates
I am trying to convert an ECEF coordinate to a geodetic coordinate using this procedure, but I don't fully understand the process. It is prefaced by stating the geodetic parameters {a,b,e,e'} are ...
1
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2answers
354 views
Calculate turn required to follow a line of latitude
Lines of latitude are not geodesic except at the equator. So to follow perfect eastern course in the northern hemisphere in a vehicle a left turn is constantly required. We can express a turn as the ...
3
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0answers
368 views
Calculate lat/long as percentage distance between two points (MSSQL)
I've loaded the US road shapes into MSSQL. I've determined the query to locate the segment of road for a specific address. The segment contains a "linestring" from a series of points.
I'm trying to ...
8
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2answers
281 views
Estimating resolution of vector data?
I got an old vector dataset with polygons covering a continent. The data was first published on paper at scale 1:5 000 000 and was later digitalized. I don't have the original data and no information ...
1
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1answer
2k views
Translating latitude and longitude into “polar coordinates” around a point
Times Square in New York City has the coordinates (as per Google Maps):
40.7589, -73.9851
The Barrymore Theater has the coordinates (again, as per Google maps):
40.7601, -73.9862
Given that ...
2
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0answers
2k views
Finding the Point of Intersection Between Two Line Segments and Level of Error
I am working on calculating the intersection of two lines. Each line segment is represented as two geographic coordinate pairs. Additionally, each line segment is less than 1km in distance.
My ...
2
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1answer
284 views
Creating local coordinate system from orthorectified image from drone
My plan is to use a drone and pix4d to map an area and produce a top down image. I have some position data that is in its own reference frame / Coordinate system.
My question is what suggestions or ...
4
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2answers
1k views
How can I calculate the coordinates of a point on the intersection of two parallel lines with a bisecting line with pyQGIS? [closed]
I am building some sort of homemade pyQGIS-Buffer-tool as the existing flat-end-buffer-tools are not working for me ( see v.distance.buffer does not create proper buffers with flat endcaps)
Therefore ...
2
votes
1answer
41 views
Determine on what side of a line my current position is at, no matter orientation
I know that this question has been up before, but I'll give it a shot since it's not exactly the same question.
Imagine a straight line consisting of a start point and an end point.
The orientation ...
2
votes
2answers
220 views
Getting lat/lng of an object X inches from the GPS? [duplicate]
I'm working on a project where I have a GPS and two receivers to create a triangle with a transmitter. The problem I'm trying to figure out right now is how can I get the position of the two receivers?...
2
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0answers
35 views
How to resolve a rectangle with know points? [closed]
How do I find the coordinates(lat, lon) for D and E in the following rectangle?
I know:
A (lat, lon)
B (lat, lon)
C (lat, lon)
AE, BE, AC
1
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1answer
506 views
Bearing to X,Y, Z
I’m working on a small project where I’m testing the ability of a laser to accurately measure the angle of a wire.
My control for the experiment gives me X,Y,Z coordinates for a point on the wire and ...
4
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1answer
653 views
How to generate missing points in GPS trajectories?
I have some GPS trajectories that include gps locations recorded on variable frequencies (every 1 min ,5 min , 20 min,etc.)using a geographic projection WGS84. In my work, i need a fine-grained GPS ...
3
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0answers
54 views
calculate turning acceleration from a compass
I have degree and timestamp and want to calculate the turning acceleration. What to trigger if the compass is turning fast.
Is there a mathematic way to get an acceleration parameter?
1
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1answer
164 views
Calculate location on line with known azimuth to point
I have the following situation (consider distances up to 300m - without great circle etc. affects):
How can I calculate the unknown location when I have all other locations in the triangle and ...
0
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1answer
51 views
Arithmetics with Coordinates [duplicate]
I wonder if I can do simple arithmetics with coordinates. Can I do substraction of coordinates like 2.570801 (lng) 46.89023 (lat) / 17.424316 (lng) 55.15377 (lat)?! Or will that get messy without a ...
5
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1answer
283 views
Index express the similarity in shape between two data sets
I have two data sets.
One is points in the blue curve. The other is points in the green curve.
Now I want to find a property (P) or something else like index that has the following characteristics:
...
4
votes
1answer
1k views
Finding Intersection of Two Circle given Lat/Lon and radius?
I am attempting to calculate the intersection of two circle on the Earth with a given latitude, longitude and radius. I started with this Calculating intersection of two Circles?
These circles will ...
2
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2answers
499 views
What mathematical processes does a GPS receiver use to determine position?
I'm writing a report on the mathematics of GPS, but I'm wondering what methods the GPS actually uses. What I've done is set up the four sphere equations and solve them using the Newton-Raphson method ...
9
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1answer
2k views
Project location on a (great circle) path
I've been searching this SE site for quite a few hours now, and I'm still struggling to find a solution to my question. My goal is that given a way in OSM and my location (lat/lon coordinates), I want ...
6
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2answers
3k views
How to convert latitude, longitude to EPSG 3857?
I'm looking to study the math involved to see how a given latitude and longitude in decimal degrees can be converted to epsg 3857. Can anybody point to a good reference or a possible python/c/c++/java ...
0
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1answer
1k views
Check if a point coordinate is between linestring coordinates
I know that, linestring is a vector and if i want to check that, if point coordinates are between linestring beginning and ending coordinates then i need to use vector comparison
(x2 > x && ...
1
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0answers
156 views
How do I compute uncertainties in the positions transformed using Helmert transformation?
I am familiar with Python, MATLAB and Mathematica. My data is given by Cartesian coordinates (positions in X,Y,Z (meters), standard deviations XX, YY, ZZ (meters) and a correlation matrix (XY, YZ, ZX)....
7
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2answers
814 views
Aerial photogrammetry book with all the math
Can anyone recommend a book that hits all the math for the general situation of doing serious photogrammetry calculations on aerial photographs?
Particularly an inexpensive book or one I can get ...
2
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3answers
2k views
How to calculate the center and radius of a circle based on points
I have a set of lat/long points. I need to calculate the center point and radius of a circle that will encompass all the points.
The co-ordinate system used is latitude/longitude as per google maps.
...
1
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0answers
136 views
How to organize/cluster nodes moving on the same direction
The Problem
I am working on a problem of clustering for mobile nodes.
Initially, I though of clustering the nodes based on their angle of movement (relative to the x-axis). However this situation ...
2
votes
1answer
423 views
Comparing compass bearings
I have several compass bearings:
bTrue = 190°
b1 = 250°
b2 = 100°
b3 = 170°
b4 = 90°
I want to compare b1 - b4 and find out how close they are to bTrue. So bTrue is 100%. How much percent is then b1,...
0
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1answer
1k views
Distance with Bearing Calculation not working
I have this function in Python that calculate distance from a point with bearing. Problem is the latitude part is generating the wrong answer and i cannot figure out where i went wrong:
def ...
0
votes
1answer
1k views
Getting GPS coordinates perpendicular and parallel to AB
I already posted this question here
And I got the solution thanks to Fang but the problem is that the coordinates I need to use are GPS coordinates and apparently GPS needs a different formula than ...
3
votes
1answer
174 views
Convert Raster into Cell by Cell Table
I'm hoping to run some Python mathematics on a raster, outside of ArcGIS. It's important to have a cell by cell table for the analysis I want to run. I plan to store it in a python dictionary similar ...
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2answers
3k views
How to take cosine squared of raster using python
I have an equation y = cos^2(x) where x is a raster.
How can I write this equation in python?
2
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1answer
513 views
Comparing two maps with two different libraries
I'm currently making a demonstration to compare the two OpenLayers libraries (2 and 3). For doing this, I have made two div elements and put the different maps on each other. The goal is to make a map ...
3
votes
2answers
116 views
Formula for charting a course around the globe, given a location and degree heading?
I'm looking for a formula that takes a long/lat coordinate and a degree heading, (e.g. "I'm standing in San Francisco and I'm facing 45º from north"), and which can draw a line across a map projecting ...
